Meeting Abstract

18.1  Sunday, Jan. 4  Genome size of bacteria in a variable endosymbiotic environment ESTES, Anne M.*; PIERSON, Elizabeth A.; University of Arizona; University of Arizona amestes@u.arizona.edu

A strong correlation exists between the degree of environmental variability and genome size in prokaryotes. Free-living bacteria such as Escherichia coli must survive periods of desiccation, starvation, UV damage and be able to use a variety of nutrients. A relatively large genome is thought to be necessary for free-living bacteria to survive fluctuating external environments. In contrast, intracellular endosymbiotic bacteria of insects are found in a specific and relatively constant host environment. These endosymbiotic bacteria have extremely small genomes as compared to free-living relatives. The tephritid olive fly, Bacterocera oleae, provides a variable environment to its endosymbiont, Candidatus Erwinia dacicola and other microbes associating with the fly. Ca. E.dacicola resides in an evagination off the digestive system in both the larval and adult stages. As the host switches from feeding on olives as larvae to feeding on nectar as adults, the bacteria encounter a different set of nutrients. Additionally, the bacteria are intracellular in the larval midgut and extracellular in the adult foregut. To survive these host developmental transitions, the olive fly endosymbionts may have a relatively high degree of phenotypic plasticity. Pulse Field Gel Electrophoresis was conducted on the olive fly symbionts and several free-living relatives to determine if the genome size is similar to free-living relatives or reduced as in other endosymbionts.